Surface modification plays an important role in micro-array biomolecule detection technology for controlling backgrounds and spot morphology. Several modifications were developed using different type of commercially available silanes such as silyl amines, aldehydes, thiols etc. for immobilization of biomolecules such as oligonucleotides. After coating the surface with reactive silanes, the next challenge is immobilization of required biomolecules on the modified surface. The surface loadings always vary with different silanes and even same silane may not give reproducible results. Reproducibility of optimum surface loading has-always been a great challenge in this field since surface loading dictates the performance of the assay. Even with simple linear molecules for immobilization, the optimum loading on the surface is difficult to achieve.
Attaching DNA to a modified glass surface is a central step for many applications in DNA diagnostics industry including gene expression analysis. In general, DNA can be attached to a glass surface either through non-covalent, ionic interactions, or through multi-step processes or simple coupling reactions. Several methods have been reported in the literature using glass surface modified with different types of silylating agents1-6. All these reported methods involve silylating step which uses expensive reagents and analytical tools. Also, these methods are also multi-step processes that are labor intensive and expensive 8-9. Earlier reported methods have involved a laborious synthesis and time consuming procedure 7. Indeed, many of the current immobilization methods suffer from one or more of a number of disadvantages. Some of these are, complex and expensive reaction schemes with low oligonucleotide loading yields, reactive unstable intermediates prone to side reactions and unfavorable hybridization kinetics of the immobilized oligonucleotide. The efficient immobilization of oligonucleotides or other molecules on glass surface in arrays requires a) simple reliable reactions giving reproducible loading for different batches, b) stable reaction intermediates, c) arrays with high loading and fast hybridization rates, d) high temperature stability, e) low cost, f) specific attachment at either the 5′- or 3′-end or at an internal nucleotide and g) low background.
The present invention represents a significant step in the direction of meeting or approaching several of these objectives.